Conventionally proposed is a method of attaching a camera to a moving body such as a vehicle etc., shooting an image of surroundings, and estimating an amount of travel of the moving body from the amount of travel of a pattern on a road surface. For example, well known is a travel amount estimating method of converting an image of the road surface shot by an on-board camera into a top view image viewed from right above, and determining an amount of travel of a vehicle using the amount of travel of a corresponding point in a top view image between two time points (for example, refer to the non-patent document 1).
Also known is a vehicle surroundings monitor device of generating a viewpoint converted image from an image of the surroundings of a vehicle obtained by capturing the surroundings of the vehicle, superposing viewpoint converted images before and after in time based on the amount of travel of the vehicle and the direction of travel, and composing a plurality of viewpoint converted images (for example, refer to the patent document 1).
Further known is a vehicle surroundings image processing device of generating a first bird's-eye view image and a second bird's-eye view image based on a plurality of images of the surroundings of a vehicle shot at different time points and calculating a motion vector which indicates the traveling state between the two images (for example, refer to the patent document 2).
Also known is a drive support system of acquiring a plurality of shot images from a camera provided for a second vehicle, and estimating a linkage angle of a first vehicle and the second vehicle according to an optical flow generated by the acquired shot images and the travel information about the first vehicle (for example, refer to the patent document 3). The drive support system derives an estimated travel locus of the second vehicle according to the linkage angle and the travel information about the first vehicle.
Also known is an image recognition device of comparing the image data of a first image with the image data of a second image, and detecting the traveling state of an object from the difference (for example, refer to the patent document 4). The image recognition device changes the comparison range of the second image depending on the speed of a vehicle.
Further known is a 3-dimensional contour position correcting method of matching the image data of a reference object obtained by an observation by a camera with the image data of a correction target which is obtained by an observation by a camera, and calculating the amount of translation and amount of rotation of the correction target (for example, refer to the patent document 5).
Also known is a 3-dimensional information recovery device of simplifying the motional condition of a camera from the restrictive condition of the rotation matrix and the translation vector between two images of a 3-dimensional rigid body, and calculating the rotation matrix and the translation vector (for example, refer to the patent document 6).                Patent Document 1: Japanese Laid-open Patent Publication No. 2003-259359        Patent Document 2: Japanese Laid-open Patent Publication No. 2003-009141        Patent Document 3: Japanese Laid-open Patent Publication No. 2009-060499        Patent Document 4: Japanese Laid-open Patent Publication No. 10-222665        Patent Document 5: Japanese Laid-open Patent Publication No. 7-318327        Patent Document 6: Japanese Laid-open Patent Publication No. 9-237341        Non-patent Document 1: Takimoto and Ito “Development of monocular ranging verification system using in-vehicle camera”, July 2006, SEI Technical Review, No. 169, p. 82-87        